little fixes

categories.html

@@ -0,0 +1,13 @@
+---
+layout: page
+title: Posts by categories
+permalink: /categories/
+---
+{% for category in site.categories %}
+<h3>{{ category[0] }}</h3>
+    <ul>
+            {% for post in category[1] %}
+                <li><a href="{{ site.baseurl }}{{ post.url }}">{{ post.title }}</a></li>
+            {% endfor %}
+    </ul>
+{% endfor %}